What they found
Landmark Northwestern paper introducing pH-triggered self-assembly of peptide amphiphiles (PAs) into nanofibers that direct hydroxyapatite mineralization aligned with the fibril long axis — mimicking bone collagen. PA design: alkyl tail + beta-sheet segment + charged head. Reversibly crosslinked with cysteine disulfides. Fibril geometry: cylindrical nanofibers, diameter ~7–8 nm by TEM. pH-responsive: assembles below pH 7, disperses above pH 7. Science 294:1684, DOI 10.1126/science.1063187.
How this applies to h09
PA nanofibers are a structural comparator to RADA16 SAP fibrils. Key difference: PAs are cylindrical (not flat tapes), rely on hydrophobic core + beta-sheet. The ~7–8 nm diameter is consistent with the 3–10 nm range seen in beta-sheet-forming SAPs. PA geometry is less directly applicable to RADA16 packing density, but supports the general principle of sub-10 nm fibril cross-sections for beta-sheet SAPs. Stupp group in vivo persistence: not quantified in this paper.
Key numbers
- Fibril diameter (TEM): ~7–8 nm (cylindrical)
- Assembly condition: pH < 7 (protonation of head groups)
- Crosslinking: cysteine disulfides (reversible with reducing agents)
- Mineralization: HA c-axis aligned with fibril long axis
Links
Connections
[see-also]STRC Horizontal Top Connector Hydrogel Hypothesis — PA as comparator scaffold class[see-also]2005-yokoi-kinoshita-zhang-rada16-reassembly — RADA16 geometry comparison[see-also]2003-zhang-rada16-biomaterials-review — SAP review contextualizes PAs